/*
 * Copyright 2010-2012 VMware and contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */

package cn.wenhao.javaClassReload.jvm;

import java.util.List;

/**
 * Provides an implementation for method lookup as suitable for 'Class.getDeclaredMethod'
 * 
 */
public class GetDeclaredMethodLookup {

    private String name;

    private String paramsDescriptor;

    /*
     * Create an object capable of performing the lookup in some MethodProvider
     */
    public GetDeclaredMethodLookup(String name, String paramsDescriptor) {
        this.name = name;
        this.paramsDescriptor = paramsDescriptor;
    }

    public Invoker lookup(MethodProvider methodProvider) {
        List<Invoker> methods = methodProvider.getDeclaredMethods();
        Invoker found = null;
        for (Invoker invoker : methods) {
            if (matches(invoker)) {
                if (found == null || isMoreSpecificReturnTypeThan(invoker, found)) {
                    found = invoker;
                }
            }
        }
        return found;
    }

    /*
     * @return true if m2 has a more specific return type than m1
     */
    private boolean isMoreSpecificReturnTypeThan(Invoker m1, Invoker m2) {
        // This uses 'Class.isAssigableFrom'. This is ok, assuming that inheritance hierarchy is not something that we
        // are allowed
        // to change on reloads.
        Class<?> cls1 = m1.getReturnType();
        Class<?> cls2 = m2.getReturnType();
        return cls2.isAssignableFrom(cls1);
    }

    protected boolean matches(Invoker invoker) {
        return name.equals(invoker.getName()) && paramsDescriptor.equals(invoker.getParamsDescriptor());
    }

    @Override
    public String toString() {
        return "GetDeclaredMethod( " + name + "." + paramsDescriptor + " )";
    }
}
